Both teams did NOT play with the same ball. The offensive team provides the balls, so when the Patriots are on offense, they use balls provided by the Patriots. When the Colts were on offense, the balls were those provided by the Colts. (So when the announcer says “it’s the Patriots’ ball”, it’s quite literally true.)
Each team gets 12 balls and there are 12 backups, plus a few balls for kicking situations.
The deflation was first noticed when a Colts’ LB intercepted one of The Great Brady’s passes and noticed how soft the ball was.
Well, we now know that the deflated balls were only used in the first half, when NE played their poorest. NE went wild in the second half when they played with properly inflated balls. Conclusion: NE is a much, much better team than Indianapolis. Didn’t NE beat the Colts badly earlier in the season - I think it was a blowout.